Big merge from experimental to bleeding edge.

sdk/lib/_internal/compiler/implementation/util/link.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of org_dartlang_compiler_util;
 
-class Link<T> implements Iterable<T> {
+class Link<T> extends Iterable<T> {
   T get head => null;
   Link<T> get tail => null;
 
   factory Link.fromList(List<T> list) {
     switch (list.length) {
       case 0:
         return new Link<T>();
       case 1:
         return new LinkEntry<T>(list[0]);
       case 2:
         return new LinkEntry<T>(list[0], new LinkEntry<T>(list[1]));
       case 3:
         return new LinkEntry<T>(
             list[0], new LinkEntry<T>(list[1], new LinkEntry<T>(list[2])));
     }
     Link link = new Link<T>();
     for (int i = list.length ; i > 0; i--) {
       link = link.prepend(list[i - 1]);
     }
     return link;
   }
 
   const Link();
 
   Link<T> prepend(T element) {
     return new LinkEntry<T>(element, this);
   }
 
-  Iterator<T> iterator() => new LinkIterator<T>(this);
+  Iterator<T> get iterator => new LinkIterator<T>(this);
 
   void printOn(StringBuffer buffer, [separatedBy]) {
   }
 
-  List toList() => new List<T>(0);
+  List toList() => new List<T>.fixedLength(0);
 
   bool get isEmpty => true;
 
   Link<T> reverse() => this;
 
   Link<T> reversePrependAll(Link<T> from) {
     if (from.isEmpty) return this;
     return this.prepend(from.head).reversePrependAll(from.tail);
   }
 
   void forEach(void f(T element)) {}
 
   bool operator ==(other) {
     if (other is !Link<T>) return false;
     return other.isEmpty;
   }
 
   String toString() => "[]";
 }
 
 abstract class LinkBuilder<T> {
   factory LinkBuilder() = LinkBuilderImplementation;
 
   Link<T> toLink();
   void addLast(T t);
 
   final int length;
   final bool isEmpty;
 }